Crowd sensors are installed in buildings at landings that have the potential for crowds to spontaneously and temporarily develop. The crowd sensors are used to provide information to a dispatch system indicating that the number of passengers waiting for a particular hall call cannot be serviced by the available space in an elevator assigned to service the passengers. In multi-deck elevator systems, the conventional method of servicing a crowd condition includes dispatching at least two elevators to the landing where the crowd is waiting. Although dispatching at least two elevators to a crowd has the advantage of providing improved service to the crowd, it has a detrimental effect on service and waiting times for passengers in the remainder of the building because fewer elevator cars are available to service the passengers in the remainder of the building.